Some aspects of murine experimental listeriosis

A set of experiments was carried out in order to approach the complex nature of L. monocytogenes infections from different aspects. Experiment 1 showed that Listeria are able to gain admission to body by numerous ways and both subcutaneous and oral entry can lead to fatal septicemia. It also gave slight support to the theory of direct neural transmission of Listeria to the brain and indicated the possibility that intestinal absorption after oral exposition at least partly occurs via lymphatic vessels. No inflammatory reaction could be caused to mice by ocular flushing with Listeria suspension.The second trial proved that there are vast differences in the animal pathogenecity of Listeria strains — even among those of the same serotype. In experiment 3A the abolishing effect of dextran sulfate on the early resistance of mice to Listeria was confirmed and it turned out that cortisone at a therapeutic dose level did not bring about that phenomenon. Levamisole granted no conspicuous enhancement of resistance in this acute challenge; however, the results of the immunity test (3B) suggested that levamisole may be beneficial during the induction phase. On the other hand, starvation appeared to impair long-term immunity. Likewise, in experiment 4 starved mice were quite susceptible to acute challenge with Listeria. Raised ambient temperature, on the contrary, prominently increased the survival rate of the animals.Owing to the fairly small number of animals these results should be regarded as preliminary starting points to further studies.     

配置500 MPa纵筋钢筋混凝土框架顶层端节点抗震性能试验研究

按照《混凝土结构设计规范》(GB 50010—2010)设计了6个配置500 MPa纵筋的钢筋混凝土框架顶层端节点,并进行了低周反复加载抗震性能试验,验证了规范规定的抗震措施对配置500 MPa钢筋的顶层端节点的有效性,分析了配置500 MPa级钢筋的顶层端节点的受力特点、节点区的破坏形态以及节点的综合抗震性能,并与受力条件基本相同的配置HRB335级纵筋节点的受力性能进行了对比,对采用不同延性指标评价配置不同强度钢筋节点的延性性能差异进行了讨论。     

Optimization of Cryoprotectant for Attenuated Salmonella Cholerae C500

The purpose of this study was to optimize the antifreeze protectant of attenuated Salmonella Cholerae C500 and improve the survival rate of C500.The effect of four types of cryoprotectant (permeating,semi-permeating,non-permeating cryoprotectants and antioxidants) on the survival rate of C500 before and after cryopreservation was investigated by single factor test.Each cryoprotectant was set at different concentrations and mixed in equal volume of C500.After two weeks of cryopreservation in liquid nitrogen,becteria plate count was carried out to calculate the survival rate,and the best one of the permeating cryoprotectant,semi-permeating cryoprotectant,non-permeating cryoprotectant and antioxidants and their optimal concentrations were beneficial to the preservation of bacteria was initially selected.Finally,the four protectors selected were tested by orthogonal test of four factors and three levels to get the optimal combination formula.The results of single factor test showed that the best permeating,semi-permeating,non-permeating cryoprotectants and antioxidants were glycol,sucrose,PVP and glycine,and the corresponding preservation concentrations were 15%,6%,6% and 0.25%,respectively.The orthogonal test showed that each factor had a significant impact on the survival rate of C500.The optimal combination formula was 17% glycol,9.0% sucrose,6.0% PVP and 0.35% glycine.The optimal combination had the optimal effect at -80 ℃,the survival rate was 88.34% in 6 weeks,followed by liquid nitrogen group,-20 ℃ group and 4 ℃ group.The results showed that the formulation of the protective agent obtained in this experiment greatly improved the antifreeze ability of C500 and its survival rate.     

大豆疫霉菌对甲霜灵、F500和氟吗·锰锌的敏感性及交互抗性研究

采用离体生测的方法测定了F500、氟吗·锰锌和甲霜灵对大豆疫霉菌野生型敏感菌株及抗甲霜灵菌株的抑制作用。结果表明,3种药剂对敏感菌株的菌丝生长、孢子囊的形成、游动孢子的形成和释放及卵孢子的形成都有较明显的抑制作用,F500和氟吗·锰锌的抑制作用优于甲霜灵,F500和氟吗·锰锌对抗性菌株的菌丝生长抑制作用明显,甲霜灵对抗性菌株的菌丝生长抑制作用不明显;药剂浓度为50μg·mL-1时,F500和氟吗·锰锌对抗性菌株的抑制率分别为97.9%和100%,EC50为0.0002μg·mL-1和0.5525μg·mL-1,甲霜灵对抗性菌株的抑制率为仅为60%,EC50为8.5024μg·mL-1,甲霜灵与F500和氟吗·锰锌无交互抗性。     

OsDUF500基因沉默提高水稻对白叶枯病的抗性

 以编码HarpinXoo 的hrf1转基因水稻NJH12的cDNA为模板,克隆到了DUF500的保守功能区。序列分析表明,OsDUF500是DUF500家族成员,功能未知。构建OsDUF500的沉默载体,用土壤根癌农杆菌介导的方法转化粳稻 R109,用Hpt抗生素做抗性筛选,获得9个再生株系。经分子鉴定,8个为沉默株系（ABD 2~9）。与野生型相比, ABD株系株高变矮,叶片变短,出现白色空秕谷。白叶枯病抗性鉴定结果表明,OsDUF500沉默株系对水稻白叶枯病的抗性存在差异,病斑长度比野生型明显缩短,病斑面积均在30%以下,株系ABD 3和ABD 5病斑面积分别为12.3%和15.7%,显示出较好的抗性。推测在稻瘟病抗性中上调表达基因OsDUF500对水稻白叶枯病抗性起负调控作用。     

500hPa距平场的EOF显著性及遥相关分析

利用空间自由度估计和自然正交展开（EOF）显著性检验方法对1948~2005年北半球冬季1月份和夏季7月份的500 hPa位势高度场进行分析,并用前10个特征值与相对应的EOF进行显著性检验。结果表明,1月份,前8个EOF比较显著,而7月份则是前9个EOF比较显著。对冬夏季前4个EOF及相应的时间系数的年际变化分析表明,北半球冬季1月份500 hPa高度距平场高空流场中存在太平洋北美型（PNA）、太平洋西部型（WP）、大西洋东部型（EA）、欧亚西部型（EU）等遥相关型;夏季7月份存在西大西洋型（WA）、欧亚型（EU）、西太平洋型（WP）、极地东西遥相关型（PEW）、东亚太平洋型（EAP）、北美东西遥相关型（NAEW）等遥相关型。遥相关型的年际变化都非常明显,从时间系数序列可以看出,1948~2005年PNA型在冬季十分明显,在1977年前大部分年都是正相关,1977年后是负相关。而夏季则是EAP型比较明显,1978年是正负相关的分界点,夏季PNA型不出现。     

西太平洋副高的年际变化及其对我国东部夏季降水的影响

利用国家气候中心给出各项西太平洋副高指数、我国东部地区108个测站逐月降水量和同期NCEP/NCAR再分析月平均高度场网格资料,分析了500 hPa西太平洋副高的年际变化特征,并通过SVD方法分析500 hPa西太平洋副高年际变化对我国东部地区降水的影响。结果表明,500 hPa西太平洋副高的面积指数和强度指数均具有准2年的周期。副高的年际变化对我国东部降水分布空间型有显著影响,第1对空间分布型的方差贡献达56%,可知副高北抬是导致我国东部夏季降水呈"-+-"的主要原因。     

500kV变电站谐振的PSCAD仿真与谐波分析

在PSCAD上对实际500kV变电站谐振进行了仿真,并运用MATLAB软件对仿真得到的谐波数据进行了波形分析。模拟了不同风电厂功率及不同串联补偿装置数值和数量条件下变电站发生谐振的情况,分析了仿真谐振波形和实际谐振波形,找到谐振原因,并据此提出了抑制谐振的方法,并在实际变电站运行中得到验证。     

500g/L氟啶胺SC对辣椒疫病的田间防治效果研究

对500g/L氟啶胺SC防治辣椒疫病(Phytophthora capsici)田间效果进行了试验。结果表明:该药剂对辣椒疫病有较好的防治效果,当500g/L氟啶胺SC含量为250mg/kg、333.3mg/kg、500mg/kg时,药后15d对辣椒疫病的防效分别为75.42%、83.68%、88.81%;药后30d对辣椒疫病的防效分别为79.02%、84.87%、90.61%,与空白对照相比其增产率分别为8.06%、13.42%、17.36%。